Re: OOC: Before the Battle Natasha certainly came. After all, this is her first fancy party in a while and she's trying to concentrate to he fact that just maybe this can work out.
She would stay close to Steve, Tony, and especially Wanda (if they're there), flirt talk with James, and happily talk to the others. She might even reach out to the non-Avengers types since she's trying to play the role of ambassador.
I'm open to all the possible interactions, so please let me know!